Enes Altun is a psychologist and a Rust developer. What he does is something very few people do simultaneously: he writes optical illusions as GPU shaders. Not mimicking known art styles, not generating abstract patterns, but translating perceptual phenomena seriously studied in vision psychology literature — Munker illusion, Café Wall illusion, Pinna rotation illusion, Adelson's checker shadow, lilac chaser — one by one into WGSL shader code, running them in real time on the GPU. He built two projects for this: rusty_art (an ever-growing collection of illusions and generative art) and cuneus (a GPU compute shader engine he built from scratch).

In the SAE framework, there is a precise remainder structure here. What is an optical illusion? It is the failure product of the visual system's chisel-construct operation. The brain continuously executes the chisel-construct cycle on raw sensory data — chiseling noise from retinal input, constructing stable perceptual objects: edges, depth, color constancy, motion direction. This process works well most of the time, and its product is "normal perception" — that is already construct, already-sediment, beauty that vision science has spent a hundred and fifty years naming. But illusions occur at the precise nodes where chisel-construct fails: when the Café Wall's gray mortar lines cause the edge detection system to generate erroneous tilt signals, when Munker's colored stripes cause the color constancy mechanism to "correct" colors that need no correction — that failure product, that thing the brain cannot stably digest, is the remainder. Illusion is the remainder of perception.

Altun's distinctiveness lies not in knowing these illusions exist — any psychology textbook covers them — but in using shaders to regenerate them. A shader is another kind of chisel-construct mechanism: it executes the same mathematical transformation on every pixel across the GPU's parallel pipeline. When you implement an illusion in a shader, you do something strange: you use a perception-less mathematical machine to precisely replicate the failure modes of a perceptual machine. The shader is not fooled by the illusion — it simply outputs the exact pixel configurations that trigger the human visual system's de-construction. This generates a second layer of remainder: the gap itself between shader computation and human perception. The cuneus engine even supports hot shader reloading and real-time parameter adjustment — you can drag sliders and watch the illusion's intensity change continuously, the perceptual remainder expanding and contracting before your eyes in real time.

The birth of cuneus itself is a remainder story. It exists because Nannou — the most important creative coding framework in the Rust ecosystem — stopped being developed. Altun explains in his README: he liked Nannou, he learned Rust through it, but its wgpu version was too old. So he built his own engine from wgpu, egui, and winit, supporting multi-pass rendering, atomics, hot reload, WASM export, audio synthesis — you can even generate music directly from WGSL shaders. Cuneus is the remainder of an abandoned dependency: the creative coding framework died, and from its ruins grew a GPU compute engine.

Where does this project sit in the naming gap? Vision psychology would not call a shader implementation "research." The creative coding community would not call serious psychophysical stimuli "art." The GPU systems programming community would not call Café Wall parameter space exploration "engineering." The Rust ecosystem sees cuneus as a shader tool but does not know why it implements Gabor patches and Asahi illusions. It sits at the intersection of visual neuroscience, GPU computing, creative coding, and psychophysics, and none of these fields will fully name it. This is the structural signature of the beauty of the remainder: it is still alive in the present, not yet sedimented into any field's construct.

Han Qin (秦汉) · @hqinjarsy · SAE Judgment & Aesthetics